One of the inventors of the present invention, Harry H. Holly, has previously invented a novel patty of plastic food material, such as ground meat and the like, as well as novel methods and apparatus for forming the patty, wherein, inter alia, the food material is forced through a foraminous member into a mold to form a patty in which the food material defines interstitial voids for entrapping air and providing retention of cooking juices to promote more rapid and uniform cooking of the patty. Such methods and apparatus are disclosed in the Harry H. Holly U.S. Pat. Nos. 4,272,864 and 4,338,702.
When food material that contains tissue fibers, especially meat and the like, is forced through a foraminous member, opposite end portions of a single fiber can be forced into different apertures in the foraminous member. The fibers, being stringy and thin, are not easily severed under the influence of conventional molding pressures.
A number of such fibers may be forced against the upstream side of the foraminous member in a manner that tends to plug up the foraminous member apertures. This tendency of tissue fibers to plug up foraminous member apertures was identified by Harry H. Holly and is described in detail in the above-referenced U.S. Pat. No 4,272,864 with reference to FIG. 23 of that patent.
Commercially acceptable methods and apparatus for forming patties of food material containing tissue fibers must have the capability for sequentially forming many hundreds or thousands of patties. If the process results in the apparatus "plugging up" with tissue fibers, the process must be terminated and the apparatus shut down to enable the apparatus to be cleaned. Obviously, frequent shut downs for such a purpose are undesirable.
The basic methods and apparatus described and claimed in the above-referenced U.S. Pat. Nos. 4,272,864 and 4,338,702 solve the plugging problem. Such methods and apparatus effectively dislodge tissue fibers from a foraminous member in a molding apparatus so as to avoid plugging up the foraminous member in the apparatus.
This basic concept, as manifested in general methods and apparatus for dislodging the tissue fibers, is set forth in the disclosures and claims in the above-referenced U.S. Pat. Nos. 4,272,864 and 4,338,702. In addition, these two U.S. patents describe a number of specific methods and apparatus for preventing the undesirable plugging up of a foraminous member with tissue fibers by dislodging the fibers. One of the specific methods includes forcing the food material first in one direction through the foraminous member and then in a second, opposite direction through the foraminous member.
Another approach utilizing the general methods of the inventions of U.S. Pat. Nos. 4,272,864 and 4,338,702 for preventing the plugging up of a foraminous member in a patty molding apparatus is disclosed in the James A. Holly U.S. Pat. No. 4,343,068. That patent describes the use of probe means that are pushed into the apertures of the foraminous member to dislodge the tissue fibers from the upstream side of the foraminous member.
Although the specific embodiments of the apparatus and methods disclosed in the above-discussed U.S. patents function well to dislodge tissue fibers from the upstream side of the foraminous member, it would be desirable to provide a less complex form of the method and apparatus for dislodging tissue fibers. Further, it would be beneficial if such an improved method and apparatus could be effected with a minimum of movement of the food material so as to avoid undesirable effects of excessive working of the food material. Excessive working of some types of food material, such as ground beef, can make the food material less tender.
Finally, it would be advantageous if apparatus could be provided for quickly and easily converting conventional patty molding machines to the improved type of molding machine wherein the food material is forced through a foraminous member. Such a "conversion" apparatus should also desirably have the capability for dislodging tissue fibers from the upstream side of the foraminous member to avoid plugging up of the apparatus.